Mobile drive mechanism

ABSTRACT

A differential gearing mechanism providing an improved mobile drive and steering mechanism for vehicles which are steered by a difference in rotation imparted to drive shafts on each side of a vehicle. The differential gearing mechanism utilizes a standard differential gearing with a drive motor connected to the gear case. A control motor associated with the gear case or one of the output shafts and rotatable therewith drives through control gears to the idler gears of the differential gearing mechanism to impart rotation to the driven gears of the differential with reversible rotation at variable speeds to vary the rotation of the output shafts connected thereto.

United States Patent Davis 1 Mar. 28, 1972 [54] MOBILE DRIVE MECHANISMPrimary Examiner--Arthur l. McKeon [72] Inventor g l z g gzggg gfi sr ggzg Avenue Attorney-Schroeder, Siegfried and Ryan [22] Filed: Sept. 11,1970 [57] ABSTRACT [21] Appl. No.: 71,507 A differential gearingmechanism providing an improved mobile drive and steering mechanism forvehicles which are steered by a difference in rotation imparted to driveshafts on each side of a vehicle. The differential gearing mechanism 58]g r k 720 5 utilizes a standard differential gearing with a drive motorconrc nected to the gear case. A control motor associated with the gearcase or one of the output shafts and rotatable therewith [56] Reterencescited drives through control gears to the idler gears of the dif- UNITEDSTATES PATENTS ferential gearing mechanism to impart rotation to thedriven gears of the differential with reversible rotation at variable g-fi speeds to vary the rotation of the output shafts connected entervathereto, 2,171,146 8/1939 Montelius... .....74/687 3.461.744 8/ 1969Booth ..74/720.5 19 Claims, 5 Drawing Figures PATENTEDHAR28 I972 SHEET 2[IF 2 INVEN'IUR JOHN L. DAV/S m E w m 7 4 MOBILE DRIVE MECHANISM Myinvention relates to a differential gearing mechanism and moreparticularly to an improved mobile drive and steering mechanism forvehicles which are steered by a difference in rotation imparted to driveshafts on each side of the vehicle.

Differential drive mechanisms for steering vehicles in this manner arebroadly old. However, they have employed complicated gearingarrangements, plural drive motors and clutches. In the presentinvention, a simplified differential gear mechanism is provided whichutilizes a conventional gear differential with a drive motor mountedtherein to rotate with v the differential frame and provide rotation tothe idler gearing to permit the driven shafts to be rotated with adifference in rotation for a desiredsteering effect. The internal motorsof the hydraulic type provide a compact easily controllable and improveddrive and steering mechanism. Control of the same is effected merely byreversing direction of flow through the hydraulic motor and toproportionately control the rotation of the same.

It is therefore a principal object of this invention to provide animproved mobile drive and steering mechanism for vehicles.

Another object of this invention is to provide in a mobile drive andsteering mechanism, an improved differential employing an internalcontrol motor and gearing.

A further object of this invention is to provide a mobile drive andsteering mechanism of this type utilizing a hydraulic motor forproviding the control rotation thereto.

A still further object of this invention is to provide an improvedmobile drive and steering mechanism which is simple in design and easyto control.

These and other objects of this invention will become apparent from thereading of the attached description together with the drawings wherein:

FIG. 1 is an exploded perspective view of my improved mobile drive andsteering mechanism with parts broken away showing the preferredembodiment of the same,

FIG. 2 is an exploded perspective view with parts broken away showing asecond embodiment of the improved mobile drive and steering mechanism,

FIG. 3 is an exploded perspective view with parts broken away showing analternate embodiment of the improved mobile drive and steeringmechanism,

FIG. 4 is an exploded perspective view with parts broken away showing astill further embodiment of the differential gearing mechanismperforming the improved mobile drive and steering mechanism, and

FIG. 5 is a sectional view of a portion of the embodiment of FIG. 4taken along the lines 5-5 therein.

My invention in the mobile drive and steering mechanism is shown in oneembodiment in FIG. 1 as comprising generally a differential gearmechanism indicated generally at 10. The gear mechanism is shown inexploded view with parts broken away to show the arrangement of partsand it receives its motive power or drive from a power source indicatedschematically at 12 driving through a drive chain 14 to the differentialgear mechanism. Power is taken from the differential gear mechanismthrough output shafts 20, 21 coupled therewith which drive through chaindrives 23, 24 to drive and steering shafts 30, 31 indicatedschematically in FIG. 1. The differential gear mechanism includes aframe structure 35 which is generally rectangular in outline and mountsa pair of bevel drive gears 38 and 40 therein. These gears are connectedto the output or power transmitting shafts 20, 21 which are journaled inthe frame 35 and disposed at diametrically opposed ends of the same suchthat the power transmitting shafts are concentric. Frame 35 also mountsintermediate bevel gears 46, 48 which are journaled on the frame throughstub shafts 50 with the opposite ends of the respective shafts beingjournaled in a mounting block 55 positioned centrally of the frame. Theintermediate bevel gears or idler gears mesh with the drive gears 38, 40to provide a conventional differential gearing arrangement. Attached tothe frame 35 is an input gear 52 which is positioned concentric with theshafts 20, 21

and is coupled to the input chain 14 leading to the power source ormotor 12 by means of which the entire frame of the differential gearmechanism may be rotated to provide input rotation and power thereto.

Positioned within the frame 35 are four control drive motors 70 73 ofthe hydraulic type. These are inside out motors in which the centralportion is stationary and the outer cylindrical portion is rotatable.Thus the central portion of each motor 75 has an inlet 76 and an outlet(not shown) at the extremities of the same for the purpose of directingfluid flow into and out of the motor. The outer cylindrical part 78 isjournaled on the stationary inner cylindrical part and includes a spiralgear surface 80 at the center thereof and conventional gearing 82 at theends thereof. The motors are reversible, that is fluid flow directedtherethrough in opposite directions will reverse the direction ofrotation of the outer casing with respect to the stationary center part.Thus the motor is a combination of a motor and a gear surface with thespiral gear 80 positioned intermediate the conventional gears 82 at theextremities thereof which rotate relative to the stationary portion withthe motor being supported by fluid lines 85 on either end of the same.The hydraulic lines are connected in common, being supported by a frame86 at either extremities of the motors and are directed as a single line87 through the power transmitting shafts 20, 21 which are hollow. Thehollow shafts may serve as the fluid conduit for the fluid flow throughto the motors and where this is utilized, a separate hydraulic rotarycoupling (not shown) may be connected between the rotatable shaft andthe stationary hydraulic lines within the frame. Where desired, aseparate fluid line may be positioned within the separate or hydraulicdrive shafts and journaled therein through suitable bearing means (notshown). Also journaled within the casing and on the centrally locatedmounting block 55 which journals one end of the shafts 50 and the bevelgears 46, 48 are synchronizing gears 90 which mesh with the straightgear portions 82 on the cases or exteriors of the control drive motorsto synchronize operation of the same. The intermediate bevel gears haveattached thereto spiral gear members 92 which are sloped or directed inopposite directions and these mesh with the spiral gear sections 80 onthe respective control motors. Thus the spiral gearing associated witheach spiral gears 92 of the intermediate bevel gears 46 or 48 will besloped in the opposite direction to provide the same direction ofrotation to the bevel gear and each of the bevel gears within the framewill be rotated in the opposite direction. At the end of each of thepower transmitting shafts 20, 21 are positioned rotary couplings 97, 98which permit rotation of the shafts and relative to stationary fluidconnections 100 leading to and from an external fluid source. Where aseparate hollow tubular shaft or conduit is provided, the hydrauliccouplings will be omitted and journaling or bearings will be provided atthis point to permit relative movement between the stationary fluidconduit lines and the rotary shafts 20, 21. The shafts 20, 21 aresupported through suitable bearing means (not shown) connected to anexternal frame apart from the frame 35 of the differential gearmechanism to support the same. Mounted on the shafts 21, 22 are outputsprockets 110, 112 by means of which the drive chain 23, 24 leading tothe drive shafts 30, 31 of the vehicle may be coupled to receive theoutput motion from the differential gear mechanism.

As will be seen in FlG. l, the control for the drive and steering of thevehicle is effected by means of a hand operated control 115 controllingthe energization of the motor 12 from a source 116. The drive motor 12which imparts the driving rotation to the differential gearing also isconnected to a pump to drive the same. The pump has associated therewitha fluid reservoir 121 supplying an inlet flow to the pump with theoutlet, as indicated by the conduit 122, leading to a fourway controlvalve or reversing valve 125. The output conduits of the control valveas indicated at 126, 127 lead to the couplings or stationary tubing 100at the ends of the differential gearing and the valve includes a returnline 128 leading to the reservoir. The drive motor may be bi-directionaland the pump will then operate for either direction of rotation toprovide an output flow through the conduit 122 to the fourway valvewhich may reverse the direction offlow through the control motors toreverse the direction of rotation of the same. The speed of rotation ofthe motor 12 or a variation in orifice opening will vary the amount offluid being pumped or the rate of fluid flow from the pump through thecontrol valve to vary the speed of rotation of the control motors 70 73.

In the operation of the mobile drive and steering mechanism of FIG. 1,input rotation is provided to the frame or differential gear mechanismthrough the input gear 52 which is attached to the frame and driven fromthe power source 12 through the chain 14. It will be understood,however, that suitable gearing from the remote power source to a gearmounted on the frame may be substituted therefore. Input rotation of thedifferential gear frame will rotate the bevel gears 38, 40 and theintermediate gears 46, 48 along with the structure including the controlmotors 70 73 and the control gearing therefrom imparting to the outputsprocket 110, 112 on the output shafts 20, 21 the same direction ofrotation. This would be at a condition when no fluid flow would bedirected through the rotary hydraulic couplings to the control motors 7073 therein. With fluid flow in a predetermined direction through therotary couplings and shafts 20, 21 to the intermediate hydraulic lines85 and to the motors 70 73 supported thereon, rotation of the casings ofthe motors and the gearssurfaces 80, 82 thereon will cause rotation ofthe synchronizing gears to insure that all motors will be rotating inthe proper direction and at the same speed. The rotation of the spiralportions 80 of the control drive motors will cooperate with the spiralgear surfaces 92 attached to the intermediate gears 46, 48 to rotate thesame. These rotations will be in the opposite direction and will impartto the output shafts 20, 21 a rotation apart from the input rotationimparted to the entire differential gear mechanism or the frame carryingthe same. Thus one shaft will move or rotate at a greater rate ofrotation than the other since the rotations of the output shafts will bein the opposite direction. This will provide a steering as well as adrive to the shafts 30, 31 associated with the vehicle for turningand/or steering the same as the drive shafts 30, 31 impart the mobiledrive power for the same. By reversing the direction of flow through thecontrol motors 70 73 which all operate simultaneously and in the samedirection, it is possible to reverse the direction of rotation of theoutput shafts 20, 21 from the previous condition increasing the relativerotation with respect to the drive shafts 30, 31 to slow down or speedup the respective rotations in either direction to permit turningmovement and simultaneous drive movement for the vehicle in eitherdirection as controlled by the rotation of the shafts 30, 31 connectedto the tread mechanism of the vehicle. Fluid flow will be directedthrough the rotary hydraulic lines permitting stationary input andoutput connections to the differential gear mechanism and the entirecontrol mechanism will be located within the interior of the bevel gearto provide a compact and solid arrangement. An external power source isrequired for driving the hydraulic source and this can be employed orincluded with the power drive mechanism as indicated in FIG. 1 through asuitable control valve 125 which is bi-directional to reverse the flowthrough the fluid flow lines and control the rate of flow therethrough.

The embodiment of the mobile drive and steering mechanism shown in FIG.2 is similar to that shown in FIG. 1 and corresponding parts will beidentified with the same numbering for simplicity. Thus the differentialgear mechanism of this embodiment includes the frame 35 having the powertransmitting shaft 20, 21 journaled therein and attached to bevel drivegears 38, 40. The same would be powered through the input gear 52attached to the frame from the power source (omitted for simplicity)coupled by means of the chain drive 14. Power would be transmitted fromthe shafts 20, 21 through the sprockets 110, 112 mounted thereon throughthe chains 23, 24 to the drive shafts (omitted for simplicity) of thevehicle. Intermediate gears 46, 48 are mounted in the frame andjournaled thereon to mesh with the drive gears 38, 40. In thisembodiment, the control drive motors 70 73 are replaced with drive gears120 123 respectively which are journaled in the frame to rotate thereinand mesh with the synchronizing gears 90 also journaled in the frame.The latter will be journaled on the shafts supporting control motor 126which are hollow to provide the inlet and outlet flow therethrough. Thecontrol gears have the straight gear portions 82 and the spiral gearportion intermediate the extent of the same and the control motor isconnected to the synchronizing gears to drive through the straight gearportions of the control gears 123 to rotate the same and through thespiral portions 82 thereon drive the spiral gear portions 92 of theintermediate bevel gears 46, 48. In this embodiment fluid flow throughthe control motor is directed through the hollow power transmittingshafts 20, 21 and through rotary couplings 88 within the frame couplingthe supporting shafts and fluid lines 89 for the control motor to theframe and the drive shafts 20, 21. The rotary fluid couplings 97, 98 arepresent at the ends of the power transmitting shafts and the shafts aresuitably journaled remote from the frame through supporting structures(not shown).

In the operation of this embodiment, input motion is imparted to theframe from the drive motor 12 and the input gear 52. Without fluid flowthrough the control motor, the entire assemblage of the differentialgear mechanism will rotate driving the power shafts 20, 21 and thesprockets 110, 112 thereon. There will be no relative movement of theintermediate or drive bevel gears under this condition. Fluid flowthrough the control motor will rotate the synchronizing gears 90 whichin turn will rotate the control gears 120 123 in the proper direction toimpart a rotation to the intermediate bevel gears 46,48. This rotationwill be in opposite directions with respect to the bevel gears such thatproper mesh with the drive gears will take place and they will rotate ina manner to add to or subtract from the rotation imparted to the frameand consequently slow down or increase respectively the speeds of thepower transmitting shafts 20, 21 journaled therein. In this embodiment areversal offlow through the control motor 126 will rotate the controlgears in the opposite direction having an opposite effect on theintermediate bevel gears and drive gears to again slow down or increasethe speed of the respective power shafts. In this manner a reversal ofrotation of the power transmitting shafts and hence the drive shaftscoupled thereto or an increase or decrease in speed of the power shaftswill take place for proper steering and driving.

The embodiment shown in FIG. 3 utilizes a control motor located outsidethe periphery of the frame of the differential mechanism and the driveand idler gears therein. As will be hereinafter identified, the controlmotor drives through a concentric shaft which is within and concentricwith one of the power transmitting shafts associated with the drivengears to rotate gearing which cooperates with the spiral gears connectedto the idler gears for driving the same. For simplicity, the details ofa motor drive source and the control source together with the drivenshafts or steering shafts of the vehicle are omitted. Similarly thejournaling of the power transmitting shafts 20, 21 apart from the frameof the differential mechanism is also omitted. Where the parts of thedifferential gearing mechanism and its drive are the same as in thepreceding embodiments, the same numbering will be employed forsimplicity in disclosure. Thus the differential gear mechanism indicatedgenerally at 10 employs the frame 35 which mounts the idler gears 46, 48and journals the same therein on their stub shafts. The driven gears 38,40 connected to the driven shafts 20, 21 respectively are journaled inthe frame and cooperate with the idler gears in a conventional manner.The input drive to the differential gear mechanism is through thesprocket or gear mechanism 52 attached to the frame which is connectedto the power source, as indicated in FIG. 1. The output or driven shafts20, 21 mount the sprockets or pulley mechanisms 110, 112 leading throughthe chain drives to the steering shafts of the vehicle as indicated at23, 24 and 30, 31 respectively in FIG. 1. These details are omitted forsimplicity. Frame 35 also mounts between the supporting plates 86 a plurality of control gears 120 123, as in the embodiment in FIG. 2, withthe synchronizing gears now being replaced by drive gears 130 connectedto the concentric shaft 132 positioned through the hollow powertransmitting shaft and connected to the driven portion of a controlmotor 134. Thus rotation of the concentric shaft 132 which is directlyconnected to the driving gears 130 of the control operates to drive thecontrol gears 120-123 by cooperating with the straight gear portions 82thereon rotating the spiral portions .80 which cooperate with the spiralportions 92 connected to the idler gears 46, 48. In this embodiment thecontrol motor is a rotary hydraulic motor carried by the powertransmitting shaft 20 which control motor includes a cylindricalstationary portion 135 and inner rotary portion (not shown) connected tothe concentric shaft 132. The stationary portion is directly connectedto the power transmitting shaft 20 to rotate therewith and suitablehydraulic couplings 140, 142 permit the transmission of hydraulic fluidor motive fluid to the control motor through stationary lines 100 fromthe fluid source with the rotary portions including lead conduits 145,146 leading to the stationary portion of the hydraulic motor to permitthe introduction and return of hydraulic fluid therefrom. With no fluidflow through the control motor, the motor, which is indicated generallyat 134, rotates with the power transmitting shaft 20 and no relativemovement occurs between the inner concentric shaft 132 and the powertransmitting shaft 20. Fluid flow through the control lines from thepower source, as indicated in FIG. 1, will cause the motor 134 to rotatedriving the inner concentric shaft 132 relative to the powertransmitting shaft 20 to rotate the driven gears 130 and hence thecontrol gears 120 123 to rotate the spiral gear portions 92 of the idlergears 46, 48 in opposite directions. A reversal in flow of the controlfluid through the control motor 134 will reverse the operation of thesame with a direction rotation of the inner concentric shaft to reversethe direction of rotation of the idler gears 46, 48 coupled theretothrough the control gearing within the differential frame to add to orsubtract from the ultimate rotation of the driven gears 38 to 40 as inthe beforementioned embodiments.

Thus in the operation of this embodiment, rotation of the differentialgear mechanism with a frame through the input rotation to the input gearor pulley 52 will rotate the differential mechanism with no relativerotation of the driven gears 38, 40 and the idler gears 46, 48 therein.Thus both power shafts 20, 21 will be driven in the same direction andmovement thereof will be transmitted through the drive sprockets 110,112 to the steering and drive shafts 30, 31 of the vehicle. With theintroduction of control fluid into the control motor 134 which isrotating with the driven shaft 20, a rotation of the concentric shaft132will take place causing the gears 130 and 120 123 to rotate andimparting a rotation through the spiral portions 92 of the idler gears46, 48 to rotate the driven gears 38, 40 of the differential mechanism.This rotation, depending upon the direction of the same, will add to orsubtract from the rotation imparted to the differential gear mechanismand the power transmitting shafts 20, 21 to provide a difference inrotation between the drive sprockets 110, 112 on the power transmittingshafts to cause a turning movement to the vehicle. A reversal in thedirection of fluid flow through the control motor 134 will operate toreverse the direction of rotation of the driven gears 38, 40 by virtueof the reversal and rotation of the idler gears 46, 48 to vary thedifference in rotation between the power transmitting shafts 20, 21 andhence the sprockets mounted thereon to the control and drive shafts 30,31 of the vehicle.

The embodiments shown in FIGS. 4 and 5 also utilize a remotelypositioned control motor in the manner similar to FIG. 3 and with adirect drive to the idler gears 46, 48 of the differential gearmechanism. As in the before-mentioned embodiments, the details of thepower driving source and the control source together with the drivenshafts 30, 31 of the vehicle are omitted for simplicity. Similarly wherepans employed in the differential gear mechanism are identical with theprevious embodiments, the same numbering is employed. Thus in FIGS. 4and 5, the differential gear mechanism 10 employs the mounting frame 35which journals the power transmitting shafts 20, 21 carrying the drivengears 38, 40 of the differential mechanism. The idler gears 46, 48 arejournaled in the frame and mesh with the driven gears 38, 40 in aconventional manner. Input to the differential mechanism is through thedrive sprocket or gear 52 attached to the frame from the remote rotatingpower source.

In this embodiment, the control motor, indicated generally at 150,drives a concentric shaft 152 positioned through the hollow powertransmitting shaft 20 which mounts the output sprocket of thedifferential gear mechanism. Control motor is mounted in a framecomprised of the frame parts 160, 162 which are connected to and carriedby the output shaft 20. The actual control motor is a rotary hydraulicmotor, indicated at 170, which receives fluid input through controllines 172, 174 leading from rotary hydraulic couplings 175, 176 mountedon the power transmitting shaft 20. The rotary hydraulic control motorhas an output pulley 178 which is coupled to a control gear 180 having apulley 182 at the extremity of the same by means of which rotation isimparted thereto through a belt type drive 184. The control gear isjournaled in flange portions 186 attached to the frame part 160, 162 andthe control gear includes a spiral portion 188 which cooperates with aspiral gear 190 journaled between the frame parts 160, 162 by theconcentric drive shaft 152. The latter is directed through the hollowpower transmitting shaft 20 and e the rotary hydraulic coupling 176 tothe differential gear mechanism 10 in a conventional manner. Within thedifferential gear mechanism 10, as will be seen in the sectional view ofFIG. 5, the power transmitting shaft 152 mounts a bevel gear 192journaled in a frame part 195. Cooperating with the bevel gear 192 arebevel gears 196, 197 connected respectively to the drive shafts orjournaling shafts 200 of the idler gears 46, 48. Thus in thisembodiment, the spiral gear portions 92 connected to the idler gears 46,48 are omitted and a direct drive from the bevel gears 196, 197 isprovided, the bevel gears being driven by the bevel gear 192 attached tothe concentric shaft and rotating with the rotation of the control motor170. By reversing the direction of rotation of the control motor, thedirection of rotation of the bevel gears 196, 197 are reversed and hencethe rotation of the idler gears 46, 48 are reversed.

In this embodiment, as in the embodiment of FIG. 3, the control motorand its mounting frame rotate with the power transmitting shaft 20 andcontrol fluid is directed thereto through the stationary hydrauliccoupling portions 175, 176 from the control valve as indicated inFIG, 1. Thus with no rotation of the control motor due to an absence offluid flow therethrough, the control motor mounting assembly 150 and thepower transmitting shafts 20, 21 rotate in the same direction with inputrotation to the differential gear mechanism through the input gear orsprocket 52 being driven from the power source. By introducing a controlfluid to the control motor, rotation of the same in one direction or theother will take place, depending upon the direction of flowtherethrough, causing rotation of the control gear 180 and the spiralgear 190 connected to the control shaft 152 to rotate the smalldifferential gear mechanism located in the mounting frame 195 which willcause rotation of the idler gears 46, 48 to impart a rotation to thedriven gears 38, 40 in a predetermined direction. The latter will add toor subtract from the rotation imparted to the differential gear case orframe from the input mechanism to vary the rotation between the outputshafts 20, 21 and hence the control and drive shafts 30, 31 of thevehicle connected to the differential gear mechanism through the drivesprockets 110, 112 mounted on the power transmitting shafts 20, 21respectively. By varying the direction of rotation and the speed ofrotation of the control motor, the amount of rotation introduced to thedriven gears 38, 40 is varied or reversed to vary the ultimate rotationof the power transmitting shafts 20, 21 of the differential gearmechanism with respect to the input rotation imparted to thedifferential gear mechanism. The latter will vary the rotation orcontrol imparted to the drive and steering shafts 30, 31 of the vehicleor with that structure connected to the drive sprockets 110, 112 of thepower transmitting shafts.

Thus in the embodiments of FIGS. 3, 4 and 5, location of the controlmotor is outside of the differential gear frame and its rotation isdirected into the differential gear frame through a concentric shaftlocated within one of the power transmitting shafts to impart a rotationto the idler gears and causing the driven gears to rotate apart from therotation of the differential gear frame.

It will be recognized that in the before-mentioned embodiments,modifications in the shape and arrangement of parts may be made withoutdeparting from the scope of the invention. Therefore I wish to belimited only by my appended claims.

What is claimed is:

1. A mobile drive and steering mechanism for vehicles which are steeredby a difference in rotation imparted to drive shafts to each side of thevehicle comprising, a differential including a frame having a first andsecond bevel gear therein and connected to first and second powertransmitting shafts in axial alignment and extending through the frameand journaled therein, intermediate bevel gears journaled on the frameabout an axis normal to the axis of the shafts and the first and secondgears and meshing therewith, power input means connected to the frame ofthe differential to provide a rotational input thereto, means within thedifferential frame and coupled to the intermediate bevel gears toprovide a rotation of the bevel gears in opposite directions about theaxis of the first and second shafts and in varying speeds, rotary motormeans coupled to the means within the differential and rotatable withthe frame from driving the intermediate bevel gears, and means on thefirst and second power transmission shafts for transmitting rotationtherefrom to the power transmitting shafts of the vehicle.

2. The mobile drive and steering mechanism of claim 1 in which therotary motor means is positioned within the frame.

3. The mobile drive and steering mechanism of claim 1 in which therotary motor means is positioned outside of the frame and coupledthereto through a concentric shaft positioned through one of the powertransmitting shafts.

4. The mobile drive and steering mechanism of claim 1 in which therotary motor means is a reversible hydraulic motor and in which thepower transmitting shafts are hollow to transmit fluid to and from themotor being coupled thereto.

5. A mobile drive and steering mechanism ofclaim 4 and including rotaryfluid couplings positioned on the ends of the power transmitting shaftsto connect fluid lines thereto.

6. The mobile drive and steering mechanism of claim 1 in which the inputmeans is a rotary power transmission means connected to the frame of thedifferential.

7. The mobile drive and steering mechanism of claim 1 in which the meanswithin the frame of the differential gearing and coupled to theintermediate bevel gears is a gear means mounted on separate supportingshafts in the frame and connected to the intermediate bevel gears on theframe to rotate the same about the axis of movement thereof.

8. A variable speed control for a pair of power driven shaftscomprising, bevel gears connected to each of said power driven shaftsand journaled in a frame, said pair of gears cooperatively and rotatablyengaging a gear means mounted in the frame to form a differential gearmechanism, control motor means mounted to rotate with said differentialgear said shafts, and control gear means coupled with said control motormeans and engaging the gear means of the differential for varying therelative rotation of the shafts.

9. The variable speed control of claim 8 in which the control motormeans is mounted within the differential gear mechanism.

10. The variable speed control of claim 8 in which the control motormeans is mounted on one of said power driven shafts and rotatabletherewith.

11. The variable speed control of claim 8 in which said control motormeans is hydraulic and including means for supplying motive fluid tosaid hydraulic control motor.

12. The variable speed control of claim 10 in which the means forsupplying motive fluid to the hydraulic control motor includespassageways in the power driven shafts and fluid conduits connected tothe hydraulic motor therefrom.

13. The variable speed control of claim 11 and including rotatablehydraulic couplings connected to the power driven shafts to provide apassage to the hydraulic fluid conduits therethrough from stationaryhydraulic supply lines.

14. The variable speed control of claim 8 in which the primary motormeans is coupled to the frame of the differential gear mechanism througha rotary motion imparting coupling connected to the frame.

15. The mobile driving and steering mechanism of claim 14 and in whichat least one of the power transmitting shafts is tubular and includingrotary hydraulic couplings associated with said shaft to provide forflow of hydraulic fluid to and from said motive means.

16. The mobile drive and steering mechanism of claim 15 in which themotive means is a plurality of motors with fluid coupling linesconnected thereto through passages in the first and second powertransmitting shafts and including a plurality of synchronizing gearscoupling the motive means to the control gear on the intermediate gearmeans.

17. A mobile drive and steering mechanism for vehicles which are steeredby a difference in rotation imparted to drive shafts to each side of thevehicle comprising, a differential including a frame having a first andsecond bevel gear therein and connected to first and second powertransmitting shafts in axial alignment and extending through the frameand journaled therein, intermediate gear means journaled on the frameabout an axis normal to the axis of the shafts and the first and secondgears and meshing therewith, rotary power transmission means connectedto the frame of the differential and adapted to be connected to a motivesource to provide a rotational input to the differential frame about theaxis of the first and second power transmitting shafts, control gearmeans journaled on the differential frame and coupled to theintermediate gear means to impart a rotation thereto causing movement ofthe first and second bevel gears in an opposite direction reversiblerotative motive means coupled to the control gear means and rotatablewith the differential frame when the first and second power transmittingshafts are rotating in the same direction to drive the control gearmeans, and means on the first and second power transmitting shaftsadapted to couple rotation thereof with the drive shaft of the vehicle.

18. The mobile drive and steering mechanism of claim 17 in which thehydraulic motive means is mounted in the differential frame and coupledto the control gear therein.

19. The mobile drive and steering mechanism of claim 17 in which thehydraulic motor is mounted remote from the differential frame and iscoupled to the control gear through a concentric shaft positionedthrough one of the power transmitting shafts.

1. A mobile drive and steering mechanism for vehicles which are steeredby a difference in rotation imparted to drive shafts to each side of thevehicle comprising, a differential including a frame having a first andsecond bevel gear therein and connected to first and second powertransmitting shafts in axial alignment and extending through the frameand journaled therein, intermediate bevel gears journaled on the frameabout an axis normal to the axis of the shafts and the first and secondgears and meshing therewith, power input means connected to the frame ofthe differential to provide a rotational input thereto, means within thedifferential frame and coupled to the intermediate bevel gears toprovide a rotation of the bevel gears in opposite directions about theaxis of the first and second shafts and in varying speeds, rotary motormeans coupled to the means within the differential and rotatable withthe frame for driving the intermediate bevel gears, and means on thefirst and second power transmission shafts for transmitting rotationtherefrom to the power transmitting shafts of the vehicle.
 2. The mobiledrive and steering mechanism of claim 1 in which the rotary motor meansis positioned within the frame.
 3. The mobile drive and steeringmechanism of claim 1 in which the rotary motor means is positionedoutside of the frame and coupled thereto through a concentric shaftpositioned through one of the power transmitting shafts.
 4. The mobiledrive and steering mechanism of claim 1 in which the rotary motor meansis a reversible hydraulic motor and in which the power transmittingshafts are hollow to transmit fluid to and from the motor being coupledthereto.
 5. A mobile drive and steering mechanism of claim 4 andincluding rotary fluid couplings positioned on the ends of the powertransmitting shafts to connect fluid lines thereto.
 6. The mobile driveand steering mechanism of claim 1 in which the input means is a rotarypower transmission means connected to the frame of the differential. 7.The mobile drive and steering mechanism of claim 1 in which the meanswithin the frame of the differential gearing and coupled to theintermediate bevel gears is a gear means mounted on separate supportingshafts in the frame and connected to the intermediate bevel gears on theframe to rotate the same about the axis of movement thereof.
 8. Avariable speed control for a pair of power driven shafts comprising,bevel gears connected to each of said power driven shafts and journaledin a frame, said pair of gears cooperatively and rotatably engaging agear means mounted in the frame to form a differential gear mechanism,control motor means mounted to rotate with said differential gearmechanism when said shafts are rotating in the same direction and at thesame velocity, a primary motor means connected to the differential gearmechanism for supplying power to rotate said shafts, and control gearmeans coupled with said control motor means and engaging the gear meansof the differential for varying the relative rotation of the shafts. 9.The variable speed control of claim 8 in which the control motor meansis mounted within the differential gear mechanism.
 10. The variablespeed control of claim 8 in which the control motor means is mounted onone of said power driven shafts and rotatable therewith.
 11. Thevariable speed control of claim 8 in which said control motor means ishydraulic and including means for supplying motive fluid to saidhydraulic control motor.
 12. The variable speed control of claim 10 inwhich the means foR supplying motive fluid to the hydraulic controlmotor includes passageways in the power driven shafts and fluid conduitsconnected to the hydraulic motor therefrom.
 13. The variable speedcontrol of claim 11 and including rotatable hydraulic couplingsconnected to the power driven shafts to provide a passage to thehydraulic fluid conduits therethrough from stationary hydraulic supplylines.
 14. The variable speed control of claim 8 in which the primarymotor means is coupled to the frame of the differential gear mechanismthrough a rotary motion imparting coupling connected to the frame. 15.The mobile driving and steering mechanism of Claim 14 and in which atleast one of the power transmitting shafts is tubular and includingrotary hydraulic couplings associated with said shaft to provide forflow of hydraulic fluid to and from said motive means.
 16. The mobiledrive and steering mechanism of claim 15 in which the motive means is aplurality of motors with fluid coupling lines connected thereto throughpassages in the first and second power transmitting shafts and includinga plurality of synchronizing gears coupling the motive means to thecontrol gear on the intermediate gear means.
 17. A mobile drive andsteering mechanism for vehicles which are steered by a difference inrotation imparted to drive shafts to each side of the vehiclecomprising, a differential including a frame having a first and secondbevel gear therein and connected to first and second power transmittingshafts in axial alignment and extending through the frame and journaledtherein, intermediate gear means journaled on the frame about an axisnormal to the axis of the shafts and the first and second gears andmeshing therewith, rotary power transmission means connected to theframe of the differential and adapted to be connected to a motive sourceto provide a rotational input to the differential frame about the axisof the first and second power transmitting shafts, control gear meansjournaled on the differential frame and coupled to the intermediate gearmeans to impart a rotation thereto causing movement of the first andsecond bevel gears in an opposite direction, reversible rotative motivemeans coupled to the control gear means and rotatable with thedifferential frame when the first and second power transmitting shaftsare rotating in the same direction to drive the control gear means, andmeans on the first and second power transmitting shafts adapted tocouple rotation thereof with the drive shaft of the vehicle.
 18. Themobile drive and steering mechanism of claim 17 in which the hydraulicmotive means is mounted in the differential frame and coupled to thecontrol gear therein.
 19. The mobile drive and steering mechanism ofclaim 17 in which the hydraulic motor is mounted remote from thedifferential frame and is coupled to the control gear through aconcentric shaft positioned through one of the power transmittingshafts.